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Hurricane Norma Discussion Number  15
NWS National Hurricane Center Miami FL       EP172023
300 AM MDT Sat Oct 21 2023
 
This morning's satellite presentation is less impressive than what
was observed yesterday.  The cloud tops associated with the central 
dense overcast have warmed quite a bit while the cloud mass
has decreased in areal coverage.  The subjective Dvorak intensity 
estimates from TAFB and SAB yield 95 kt while the objective 
analyses from UW-CIMSS average around 100 kt.  Based on
these data, the initial intensity is lowered to 100 kt for this 
advisory.
 
Although most of the dynamical and statistical intensity models
show gradual weakening through the period due to increasing shear
and a stabilizing surrounding atmosphere, Norma is still expected to
be a hurricane while it moves over the Baja California peninsula 
later today.  Toward the end of the period, Norma is expected to 
move inland and over the higher terrain of the state of 
Sinaloa on Monday and quickly dissipate.  The official intensity 
forecast is similar to the previous one and closely follows the 
various consensus intensity aids.
 
Norma's initial motion is estimated to be northward, or 360/8 kt,
with the hurricane moving between a deep-layer trough to its 
northwest and subtropical high pressure located over central Mexico. 
A turn to the northeast to east-northeast is forecast this evening, 
while the hurricane moves over the southern Baja California 
peninsula and rounds the northwestern periphery of the 
above-mentioned mid-tropospheric high.  On the forecast track, Norma 
should emerge over the Gulf of California and approach the Mexico 
state of Sinaloa coast on Monday.  Although there is some 
along-track forward speed uncertainty in the global and regional 
track guidance, the HFIP HCCA corrected consensus model has been 
fairly consistent in both Norma's predicted forward speed and track 
trajectory, and the NHC forecast follows suit.
 
 
Key Messages:
 
1. Norma is expected to bring life-threatening hurricane conditions
and a dangerous storm surge to portions of the far southern Baja
California peninsula within the hurricane warning area today and 
tonight.  Preparations to protect life and property should be 
rushed to completion.
 
2. Heavy rains from Norma will begin to impact the far southern
portions of Baja California Sur today, continuing through Sunday,
with heavy rains reaching Sinaloa also today, continuing
through Monday.  This rainfall will produce flash and urban
flooding, along with possible mudslides in areas of higher terrain.
 
3. Norma is forecast to approach the west coast of Mexico as a
tropical storm on Sunday night and Monday, and a Tropical Storm
Warning is in effect for a portion of that area.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 21.7N 110.1W  100 KT 115 MPH
 12H  21/1800Z 22.7N 110.1W   90 KT 105 MPH
 24H  22/0600Z 23.5N 109.7W   75 KT  85 MPH...INLAND
 36H  22/1800Z 23.9N 109.0W   65 KT  75 MPH...OVER WATER
 48H  23/0600Z 24.2N 108.1W   50 KT  60 MPH
 60H  23/1800Z 24.7N 107.0W   35 KT  40 MPH...INLAND
 72H  24/0600Z...DISSIPATED
 
$$
Forecaster Roberts
 
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